Why is full size case resizing not recommended? I've reloaded quite a bit over the years. .243, .300 Win Mag, lots of .303. I always thought bringing a case to OEM was the way to go. If there's a better way, I'm all ears!

If you fully resize the case, such that the she!! holder is pushed with firm contact to the base of the F/L die, the shoulder of the case is pushed back to original cartridge specs. These chambers are made to accommodate the cartridge plus a lot dirt, and still be able to close and lock the bolt. So the shoulder gets blown forward upon firing. F/L sizing will cold work the shoulder of the case and it will soon crack from a few reloads. I also think that this procedure quickly results in case head separations (circumferential cracks around the case body about 1/4 inch above the case head) as the body of the case streatches to fill the chamber.

Neck sizing avoids this and will greatly extend the life of the cartridge case. Alternatively, back the F/L die out of the press enough so that the shoulder of the case is just touched by the die. Others have posted a procedure to follow for sizing in this manner.

Lee Enfields tend to have generous chambers being military rifles and case expansion is much greater than with a hunting rifle. If you full length resize you are moving a lot more brass than with a 243 sporter. Case life will be half than it would be if you neck size. Each of my 303 rifles has its own set of brass generally loaded 10 times

Thanks Shamu. I will give it a read. I just got back from the range. Dialing in the No4 Mk2 sniper clone. I had loaded some 180 Sierra Prohunters with 38 gr H4895, and the same with 39 gr H4895. Three shot groups @100 yds. 38 gr... 1.23". 39 gr... 1.16". Very happy!

it's fair to say that neck sizing only is best for accuracy; and if you've only got one Enfield rifle it's pretty straightforward. I started out doing it this way. But since I've now got more than one rifle in .303 it get's a bit more complicated. You have to keep the brass seperate because the chamber's vary slightly.

It's easy to pick up the wrong box and find the bolt won't close when you get to the range. (been there, done that and got the Tee shirt!)

So now I full length size to avoid the mix up. When I have more time I will probably get the brass better organised and start neck sizing again. But that means cleaning prepping and loading brass for each rifle. You can end up with a lot of can's of brass, dirty for rifle A,B or C, cleaned, trimmed, formed. Then extra ammo boxes for each rifle

I didn't go into it in detail, because it was intended to be more of a primer/intro than a really in-depth discussion.

Basically you do what the article describes for each rifle, then you not the number of degrees turned & in which direction for each rifle. This is basically using the lock ring threads as a micrometer adjustment to compensate for chamber differences..

Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)

There is a school of thought that it is essential for optimum accuracy for the bullet to be absolutely concentric with the bore when the powder is ignited. By F/L sizing, the case body diameter is reduced back to cartridge spec dimensions. This allows for some radial offset of the case in the chamber such that the bullet will self align to the bore.

I will say that I have not notice any degradation in accuracy by F/L sizing the case. By that, I mean using a F/L die that is backed out of the press to only “bump” the shoulder back to allow the bolt to easily close and the cartridge to headspace on the rim. Is it more accurate than neck sizing? Well, I might just have to do some testing to find out.

Interesting read, Shamu. I guess I've been doing a form of neck sizing after all. When I first started reloading, and old fellow that shot .303 told me to have a space the width of a dime between the die and the she!! holder when sizing/depriming. I've done that all these years without really knowing the mechanics of it.

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